Example embodiments of inventive concepts relate generally to semiconductor memory devices and, more particularly, to a redundant array of inexpensive disks (RAID) storage device and a method of management thereof.
Flash memory devices have been widely used as an audio and video data storage media of information devices such as a computer, a smartphone, a personal digital assistant (PDA), a digital camera, a camcorder, a voice recorder, an MP3 player, and a handheld personal computer (PC). However, an erase operation is necessarily performed in advance to write data into a flash memory, and a unit of written data for a flash memory device is greater than a unit of erased data. This feature prevents a file system for a typical hard disk from being used as it is, even when the flash memory is used as an auxiliary memory device. Moreover, this feature implies that sequential input/output processing to a flash memory is more efficient than non-sequential input/output processing.
A representative example of a mass storage device based on a flash memory is a solid state drive (hereinafter referred to as “SSD”). The demand for SSDs is tremendously increasing, and purposes for which SSDs are being applied are diversifying. For example, an SSD may be employed as an SSD for a server, an SSD for a client, an SSD for a data center, and the like. An interface of an SSD should provide optimal speed and reliability according to each of the purposes. SATA (Serial Advanced Technology Attachment), PCIe (Peripheral Component Interconnect Express), SAS (Serial Attached SCSI), etc. have been applied as an SSD interface to satisfy the requirement.
Additionally, a storage system including a plurality of storage devices is used to achieve high reliability. For example, a redundant array of independent disks (RAID) storage system partitions single data and stores the partitioned data in units of chunks after distributing the partitioned data to a plurality of storage devices. Since there is little chance that the plurality of storage devices all suffer from a problem at the same time, the storage system may ensure a high reliability of data. For example, even if one of these chunks is lost due to damage or loss to one of the storage devices, the data may still be reconstituted correctly if error correction coding or parity is applied to the data before it is partitioned.